"If we confess our sins, He is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness." (I John 1:9)
Salvation cancels sin's penalty and power, but not necessarily sin's presence. We, as Christians, are prone to sin. There are those who would teach a doctrine of sinless perfection or total eradication of the sinful nature, but even the apostle John disagrees. In fact in verse 8 he states: "If we say that we have no sin, we deceive ourselves, and the truth is not in us." I don't believe that eternal security is a blank check for sin, nor do I believe that a person can use grace as an excuse to live disgracefully. While we are waiting the 'redemption of our bodies' the Bible teaches us the great blessing we have in confession. Confession, not as taught by an apostate church, i.e. telling some parish priest about our sins. But rather with a contrite heart, approaching the throne of God with thanksgiving and praise, and telling Him (God) all about our sins and failures. This is a privilege that we as believers have (see 1 Peter 2:9). To go to God directly as priests ourselves, because Jesus Christ has made a way for us to approach God.